Bell County dropped two letter grades in the American Lung Association’s 15th annual State of the Air report released last week. In line with a reported nationwide trend, the county was downgraded to a “D” in terms of area ozone quality.
The American Lung Association rated counties across the nation, with “A” being the best grade, down to the worst grade of “F.” The ratings are based on data from the U.S. Environmental Protection Agency, which measures and regulates pollution and ozone levels.
“Most people first hear of ozone as atmospheric ozone, which helps block (ultraviolet) rays from the sun,” said Jenna Durant, spokeswoman for Region 6 of the Environmental Protection Agency.
There also is ground-level ozone, however, which are air pollutants not emitted directly but compounds formed from other pollution, she said.
Ground-level ozone causes greenhouse gases and irritates people with sensitive lung conditions, such as
asthma. According to the State of the Air report, the county received a lower ozone rating because the EPA issued a “code orange” alert in the area for seven days in one year. A code orange means the air quality could be unhealthy for sensitive residents and has scored between 101 and 150 on the air quality index.
The index measures the five pollutants regulated by the Clean Air Act — ground-level ozone, particulate matter, carbon monoxide, sulfur dioxide and nitrogen dioxide. Scoring more than 300 on the air quality index indicates a “very unhealthy” atmosphere in which the EPA advises all people limit outdoor activity.
Durant said the biggest contributor to ground-level ozone formation is nitrous oxide, carbon monoxide and heat. Car exhaust is a big contributor, and driving a car around in the middle of a hot day is one way to increase “bad” ozone days, she said.
Ken Roberts, Texas Department of Transportation spokesman, said the Killeen area can have up to 100,000 vehicles per day on U.S. Highway 190.
“Those numbers rival what we see on (Interstate) 35,” Roberts said.
Close to 1,000 people move to Texas every day, he said, and with an increase in people, there is an increase in the number of vehicles.
The Texas Commission for Environmental Quality said it does not agree with the ALA grading system and believes it does not accurately represent air quality in the area.
“The Killeen area (Bell County) is in attainment for all federal air quality standards ... In this case, the area receives a substandard grade when it is meeting the EPA standard that is set to protect the most sensitive individuals,” said Andrea Morrow, spokeswoman for TCEQ. “Also, the grading assumes an entire population is exposed to the highest measures monitored in the county which we know can significantly overestimate potential exposure.”
The TCEQ takes measurement averages to determine if area air quality is considered safe and in regulation with EPA standards.